Existing communication systems are sender directed. That is, such systems enable a calling or a transmitting party to contact any one of a plurality of receivers to transmit and receive data to and from the called receiver based on a connection. The sender directed system operates to provide a communications link one at a time. In this way, either a designated frequency or some code indicative of each location is a messenger. For example in systems such as telephone systems, any party can call another party within a wide spectrum of subscribers or conference calls can be made. Subscribers require the dialing of a unique code whereby each subscriber to the systems has a code (telephone number) at which he can be reached. Thus, connections can only be made based on the knowledge of this code or based on a particular frequency in regard to other systems and so on. Such systems do not allow independence of use or concurrency. They require either time connection or compatible frequencies to afford communications. The system enables only "called" parties to communicate with "calling" parties.
The present system, which will be described, operates in a manner to provide independence of use while providing omni-directional propagation in the radio medium. The present system is capable of concurrent activities through multiple sources and essentially allows information exchange which results from use of a time dispersed redundancy coded signal format which also allows timing and access flexibility, concurrency, and independence of users and usages. The system to be described is distinctly different from the traditional systems as the system supports simultaneous transmissions where all transmitted signals are presented at each site for reception, even if the transceivers are transmitting to and receiving from others.
As one will understand, the system operates similar to acoustic communications which occur at a cocktail party. In this manner a great number of people can communicate with each other or with anyone across the room and so on. Hence, each of the participants of a cocktail party can communicate with any other person at that party and do so while talking and with more than one person listening or engaging in the conversation. There is no communication system according to the prior art which operates according to this analogy.
As will be explained, the present communication system allows every single subscriber to have access to every single transmitted message and to receive any message so desired with any message capable of being received by more than one unit and capable of being received while the unit is transmitting. Thus by eliminating conflicts, as compared to prior art communication systems the system increases capacity by an order of magnitude, gives each subscriber total accessibility to the community transmissions, and allows each subscriber to select for reception only data which is relevant to itself. The system operation, essentially, can be analogized to the brief description of the cocktail party as indicated above.
The system is particularly suited for military communications, as existing communications equipment will not meet the requirements resulting in emerging operational needs to better coordinate dynamic tactical engagements. Traditional communication structures are poorly suited for the dynamics of coordinating functions such as sensor coordination, detection enhancement, targeting, maneuver coordination, weapon coordination, and kill assessment.
The communications scenario for cooperative information sharing are characterized by networks or groups of subscribers with access to other subscribers information. Each subscriber needs total access to community generated data and an ability to select for reception only data that is relevant.
Current channelized radio systems provide only fragmented connectivity, can not provide total accessibility, and suffer serious loss of a platform's transmission capacity as its community size increases and receptions block use of transmitter. Identified needs for information sharing between force elements are real, can be expected to increase, and will overwhelm the capacity of existing structured communication systems. The inability of traditional communications to support these needs will inevitably result in truncation of a group's real requirements, minimal sharing of information among groups, and thereby, reduced battle-force capability. Traditional radios, with their reliance on time and frequency guardbands have inefficient system capacity due to their inefficient use of time and frequency spectrum resources. The basic cause of the inefficiency is traditional radio's inability to receive while concurrently transmitting. As one will understand, a radio's transmitter always served as a jamming or interference source for its receiver.
In a community of diverse platforms and multiple media, effective data exchange is frustrated by mismatches in radio circuit structures, timing, and link protocols. These structures and protocols have been used to organize participation to prevent transmitter blocking of receptions and vice versa. Many types of sequential access protocols have been developed to deal with the current necessity for sequential, mutually exclusive transmissions and receptions.
Data interoperability would benefit significantly from technology which eliminates the need to protect receptions from transmissions. High quality, secure, economic, hear-while-talk, bandwidth efficient voice communications is a long standing need. Previously, low cost voice digitization solutions required too much bandwidth; lower bandwidth solutions required costly processing and are vulnerable to noisy acoustic environments. Traditional radio's constraints also demand the complex preassignment of communications resources. The communications planner preassigns frequency channels in time slots in order to separate transmissions and receptions while attempting to achieve the kind of activity that satisfies the missions communications needs. A communication system is needed which avoids the complexity of the communication planners tasks; gives the platform more capacity, more autonomy, and dynamic platform-determined accessibility to data; and addresses the growing needs to support the real time engagement coordination functions.
Many communications systems employed today with their sophisticated spread spectrum and/or frequency hopping techniques tend to have poor reliability. Radios with good mission reliability will be more essential as information exchange between friendly forces becomes increasingly important to mission success. The communication system to be described has applicability in regard to military and other communication systems where the platform diversity may include aircraft, ground transportation, as well as sea-going vessels.
The overall object of this communication system is to increase available system communication capacity by an order of magnitude. The system provides total access to the community's transmissions and overcomes today's fragmented connectivity. The system further allows each subscriber to dynamically select for reception only those data messages or voice that are relevant to that subscriber. The system enables hear-while-talk voice as a low cost function within the multi-function transceiver employed. The system further provides data inter-operability by use of a single common basic waveform structure and by avoidance of circuit oriented timing structures.
These and other aspects of the system provide improved mission reliability and simpler maintenance through a radio architecture based on pooled, simplified functional modules and automatic fault isolation.